The present disclosure relates to an apparatus for replacing a gear reducer, particularly to an apparatus and method for installing and removing a gear reducer from a robot (e.g., a Fanuc robot). Gear reducers are used in several assemblies to facilitate a transfer of energy from a motor to other components of the assembly. As with many mechanical components, the gear reducers may need to be removed and replaced, or simply removed for maintenance and/or cleaning. However, the gear reducer can be relatively heavy and/or large, making hand-held removal and proper installation difficult.